The image
below is our new basement arrangement with Ground Source heatpump in the center, ground loop pumps
on the left, and new heatpump water heater on the right with old tank preserved in line as a backup
for Christmas visitors.
Note, our house is heated by hotwater cast-iron radiators and so the heatpump is a water-to-water unit
and not as common as most modern homes with HVAC duct work. Since we have no ductwork, we
can only take advantage of the GS heatpump for heating only (no cooling yet)... In the far back
is a homemade 10 kW electric backup heating system for emergency backup also described.

Having
switched to Hybrid and Electric cars
in 2007/8 to reduce our use of oil by 50%, and
Solar in 2011
to eliminate
our coal emissions, our #1 remaining fossil fuel source was the 1000 gallons of heating oil we
were burning at ever increasing price. In 2012 oil was up to $3.50 a gallon only slightly less
than gasoline!
The knock-outpunch was when we realized that at $3.50 a gallon for heating oil, it was as expensive
as stright electric resistance heat, the most expensive form of heat! Time to switch to the 4-to-1
savings of a ground-source heat pump.

Efficiency is the Goal: The main purpose of this page is to share my lessons learned which are
counter to all advice received from all sources. In a nutshell, The HVAC industry is based entirely on
"performance" just like Detroit and the Auto industry that for decades hangs all their production and
advertising on the singular focus of "performance". When in fact, some people want "efficiency"
foremost. What we discovered was that the typical ground-source heat pump system is designed for
maximum performance and fastest response times even though such design significantly sacrifices efficiency
sometimes over 30% on milder winter days!.

No Storage Tank: What is notably absent in the above system photo is the very large
hot-water storage tank that is normally "required" in a water-to-water hydronic heat-pump
system.
In such typical systems, the heat pump is designed to always maintain this storage
tank at a set high temperature and then as the house demands heat, the radiator system water
is circulated from this tank, giving a quick response. The heatpump operates independently
to simply maintain the storage tank temperature. What made no sense to me was this
design to always pump heat to the tank at 120F even if the house would do fine with 100F
water in the radiators during most winter days.

Heatpump performance is inversely related to temperature
as shown here in
blue.
The black line shows the increasing electrical requirement for higher
temperatures and the
red
line shows the resulting efficiency in BTU per kWh. As you can see,
the lower the radiator water temeprature, the higher the performance and lower cost.
The difference between operating at 120F and 100F is a coeficient-of-performance (COP) difference of 2.6 vs 3.1 or a 20% loss.
If the storage tank temperature is set to 125F for worst winter day and most winter days can do
with 95F water, then the diffrerence is almost 33%!

It is also worth noting, that without the
storage tank, every cycle of the heatpump system begins with the radiator water having cooled
down below 70F. So the first majority of each cycle is actually operating in the more efficient
upper left portion of the red curve.

Fighting for a Tankless System: None of the HVAC contractors would consider a tankless
system because "thats just now how we do it. A tank is required." Yet the installation manual
from the manufacturer was less stringent... that is, "recommending" a storage tank in some
paragraphs and saying it was "required" in others. My frustration was the inabilty to talk directly
to a real thermal engineer. Getting blocked at every turn by salesmen, installers, and middlemen of
all stripes. Finally I got to someone at the manufacturer (still not an engineer) who did agree,
that operating
the heatpump at a lower temperature was more efficient and less demanding on the hardware, but he
still could not "recommend it" for the following reasons (and my counterarguments):

Danger of radiator scale getting into the HP heat exchanger - N/A since there would be a filter on the input

Danger of loss of circulation on HP output - N/A since all our radiator valves are rusted open

Danger of short-cycling - N/A, our old radiators hold 180 gallons of water compared to their 80gal storage tank

Poor response time - Only when doing big thermostat set-backs, and no worse that with oil.

Tankless Install: Other thermal and mechanical engineers where I work (though, not
specifically HVAC engineers), all agreed that operating at lower
temperatures as a matter of routine would be more efficient so I finally found a
contractor
that would install the system without the storage tank and would install the added temperature,
pressure, and flow gages that I requested. Though, he put a clause in the contract that
without a "storage tank, performance was not guarnateed". Besides, his price was also
the best price. Oh, and the other contending contractor lost the job when he said something like
"my father has been doing these for 30 years and that is just the way we do it"... implying to
me that no one was really engineering these systems, just turning the crank.

Trenches: The photo at right is the 4' deep trench with the header piping
to three of the four 300' wells. The 4th well is 20' around the far corner to the right. The 4th
is near the buldozer in the photo farther down the page.

Primary Mode - Gotcha! Once the system was installed, it was immediately obvious why a storage tank was "required".
And that is because the control system only does one thing. Drive the HP compressor until the return
circulating water reaches the 120F setpoint (tank set point) completely independent of the house
thermostat. So the house just kept rising in temperature until every radiator in the hosuse was at
the "tank's 120F set point" even though there was no tank. This is called "Primary mode".

Secondary Mode: Next we tried
secondary mode, where the HP would respond to an external thermostat (in the house). This worked great
except now, it ignored the maximum water "set point". This is not really a problem except in the
case of deep temperature set-backs. If we set back the heat by 5 degrees, then when the timer
later bumped it up by 5 degrees, the HP would run max out until the house was satisfied, and this could
let the heat pump go all the way to its maximum output even if it was not needed.

Engineered-Fix#1: What we came up with was to use spare contacts on the house thermostat relay to
not drive the heapump directly, but to simply parallel a fake-themsister across the aquastat max-set-point
themrister so that when the house was "satisfied" then the heatpump thought the water was already at max
temperature and would shut down. When the house needed heat, the paralleled virtual thermister would be
disconnected by the relay contacts
and the heatpump would notice the water was below the set point and would crank up. In this
manner, we would have the house thermstat control AND the auotomatic closed loop aquastat keeping the heatpump
operating below its peak temepratre. (but we have not done this, see below).

Engineered-Fix#2: Blow air across the radiators! Actually, this fix works so well, that I have
not even gotten around to Fix#1. I just placed some of our summer fans directed at some of the
radiators in the house. Now not only does the house warm up faster, but
the circulating water never gets close to the maximum of the heatpump and so all of our heat is now
coming at a much lower temperature. Note, I only placed fans where aesthetically acceptible to the wife,
as shown here in the dining room (with outdoor plants in for the winter),
but it turns out that with fans on 6 out of about 15 radiators, the house temeprature is wonderful.
We now set at 68F and are enjoying winter life, where with Oil, we only set to 65F for guests and
shivered around 62F the rest of the time.

Fans for convection: The fans aren't all new to us.
We had already grown accustomed to placing a box fan in front of a radiator
in a room where we were going to be for a while to improve convection there while keeping the rest of
the house more economical. It also has the advantage of not having to go open and close radiator valves
throughout the house to move heat around. See our other fans in the
living room,
playroom,
game room, and
kitchen.
The kitchen has our only baseboard heater and so I had to build a small box with some box fans in it
as shown here flipped over. The two box fans are wired
in series to make them very quiet and the box makes a nice sleeping platform for the fat cat that
then overlaps onto the narrow baseboard. Though this arrangement only blows air under about 1/4th
of the baseboard and is still inadequate to fully heat the kitchen without an aux electric baseboard heater.
I have added a "tower" fan as well, but it is too noisy even on low and we both dont like the
looks, so it goes away before guests.

Shopping around for $5 fans at the flea-market found enough fans that we could select the most quiet ones
and chuck the noisy ones. I also ran a circuit around the house with small outlets by each of these radiators
driven from the heat-pumps load circulating pump circuit. This turns the fans on and off with the heat and
also makes it easy to connect the fans once a year between seasons.

Emergency Backup Heating: To provide emergency heat during power outages or in case the HP needed
work, I installed a pair of 4800 W electric water heater elements inside a 3' piece of 2" galvenized pipe
as shown at right This 9600 W
worth of heat can provide about 33,000 Btu but at a cost of about $1.50 an hour or about $30 a day
for 20 hours run time on very cold days. Surprising, straight resistive electric heat (at 10c/kWh)
is no more expensive than heating oil when oil is at $3.50 a gallon or higher.
Caution: There must be circulation! If the circulator pump
would fail, the water will boil and over presurize the system.
Presumably the relief value would blow and the
heating elements would then self distruct (though contained safely within the pipe).
So I will use a surface contact
over-temp thermal cutout to sense any abnormal heat rise. When it steams, the 3" pipe heats up to boiling
almost instantly from its normal 95 F to 100F normal operation.

PRIUS Emergency Power: The plan is to use my
Prius for Emergency power to power these heater elements.
The beauty is that
these two 4800 W elements can be connected directly to run at 240 VDC from the Prius High Voltage
system. My car has outlets on the back for access to both 10 kW of 240 VDC power and about 1 kW of
120 VAC. The car should be able to provide the 10 kW from its 18 kW MG1, but the
challenge is to make sure the engine stays running.
Normally the Prius will start and stop the engine as needed to keep the HV battery charged, but at this
10kW load, I don't want the engine to be starting and stopping every fraction of a minute. I need to
find the right load so that it runs all the time (this has not yet been tested). Bob Wilson suggest spoofing
the engine thermostat to make it appear cooler than 40C and the engine will automatically run to
maintain engine temp (to keep emissions low).

Solar Emergency Power: Although my
grid-tied solar also ceases operation when the grid
goes down, I still have about 8 kW of solar DC power
available. The system consits of three arrays of panels providing about 2.8 kW each at 480 volts to three
separate grid-tie inverters. During power outages, I can simply parallel the 480v outputs of
all three arrays and connect this to the two 4800W heating elements in series to provide a nice
matched load. Caution: All high voltage DC wiring inside a dwelling must be in metalic conduit
since a slight bad connection becomes a 3000 degree welding arc and is not self-quenching like AC.

Conclusion and Phase-2:
So with the solar during the day, and the Prius at night, we can at least get
33,000 Btu of heating during power outages. Phase 2 of the system would find a way to take
all the waste heat of the Prius gas engine and get that inside the house. That would double
the heating capacity! Call it co-generation.

Geothermal Installation Impact: For us, the installation impact was enormous! The reason being, that
the only place we could get the Well drilling truck was in our front yard, and our front yard was 100%
driveway, plantings, or gardens. The
drilling truck
was 30 feet long and needed at least 13 feet of overhead
clearence just to get in, and then needed 33' of clear sky vertical clearance over the wells. This
involved supstantial tree trimming as well. The photo here shows the impact on our driveway
after the well drilling rig has left and then the connecting trenches were dug. The
entire 3400 sqft concrete circular driveway had to be dug up and hauled away to clear room
for all th is work.

THE REMAINDER OF THIS PAGE HAS NOT BEEN EDITED YET AND IS A CARRY OVER FROM OTHER PAGES